a. Field of the Invention.
The present invention relates to a method for producing lysine ester from .alpha.-amino-.epsilon.-caprolactam.
B. Description of the Prior Art.
Lysine ester has been used as a synthetic intermediate for producing a monomer of polyurethane having no yellow coloring, which is an additive for polyamides and various medicines.
Lysine ester has been produced by esterification of lysine in the presence an acid catalyst. This method, however, is not necessarily satisfactory for commercial production of lysine ester, because the starting material, lysine, is very expensive. Furthermore, in the esterification of lysine, the reaction rate is gradually reduced corresponding to dilution of alcohol, which is used as both reactant and solvent, by the production of water from esterification reaction, and therefore it is difficult to complete the reaction. The recovery of alcohol from waste containg also water and an acid catalyst such as hydrochloric acid is another problem in this method.
An object of the present invention is to provide a novel method to produce lysine ester. Another object of the present invention is to produce lysine ester directly from .alpha.-amino-.epsilon.-caprolactam in a high yield and conversion.